A method for determining a temperature or temperature distribution in an object region having a composition consisting of n different material components is known from the disclosure of the publication DE 10 2008 049 604 A1, wherein:                an X-ray computed tomography system is used, by way of which image data sets can be recorded at different spectral distributions of X-ray radiation,        image data sets of the object region are recorded at n different spectral distributions of the X-ray radiation by way of the computed tomography system,        densities, attenuation values or CT values for the n different material components which have a known dependence on the temperature as well as possibly on the location in the object region are determined from the image data sets by material decomposition, and        the temperature at one or more points of the object region is ascertained on the basis of the determined densities, attenuation values or CT values as well as of the known dependence of at least one of the variables on the temperature and possibly on the location.        
According to the known method, an X-ray computed tomography system is therefore used, by which image data sets are recorded at different spectral distributions of the X-ray radiation. In order to ascertain the temperature or temperature distribution in an object region which is composed of n different material components, the computed tomography system is used to record n image data sets of the object region at n different spectral distributions of the X-ray radiation. From the n image data sets the densities, attenuation values or CT values for the n different material components are then determined by way of the known material decomposition technique. The temperature at one or more points of the object region is then ascertained on the basis of the determined densities, attenuation values or CT values as well as of the known dependence of said variables on the temperature. In this case the dependence of the density of the respective material on the temperature can be derived from tables or determined in advance by means of measurements.